Density of states of electrons bound to impurities in quantum wells of GaAlAs/GaAs

• Published in: Surface science 1988, Vol.196 (1), p.352-354
• Main Authors: De Andrada E Silva, E.A., Da Cunha Lima, I.C., Ferreira Da Silva, A., Leal, C.E.
• Format: Article
• Language: English
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/0039-6028(88)90707-8

The DOS for electrons bound to impurities in quantum wells of GaAlAs/GaAs heterostructures is calculated according to a realistic model that takes into account diagonal disorder due to dispersion in binding energy and off-diagonal disorder due to randomness in the transfer matrix element. The interfaces. The second one results from the structural disorder. A method is presented which applies when the ratio between the impurity layer thickness Δ and the most likely distance between impurities R ̄ is small. For instance, if the impurity concentration is 10 15 cm −3 and Δ = 100 Å, Δ/R̄ = 0.079. If the well width is in the range 100 ⩽ L ⩽ 600 A ̊ we find that both diagonal and off-diagonal disorder are of the same order, giving a band width in the range 1.2–5.5 meV. The off-diagonal disorder starts to become dominant as the number of impurities per unit area increases.